FCC moves toward 'historic' spectrum sharing plan

The U.S. Federal Communications Commission has approved what some commissioners called a "historic" plan to allow private mobile broadband services to share spectrum with incumbent military users.

The FCC voted Friday to approve its so-called Citizens Broadband Radio Service (CBRS) plan to open up wireless frequencies from 3550MHz to 3700MHz to new users, including new devices that could use the spectrum like current devices use Wi-Fi.

Commercial access to the spectrum may still be years away, and the FCC has several sticky issues it needs to resolve, including questions about the best ways to limit inference between users in the band. But with little new spectrum available to satisfy skyrocketing demand for mobile data services, some commissioners hailed the spectrum-sharing plan as a new model for dealing with a spectrum shortage.

"Since they don't make spectrum anymore, and since spectrum is the pathway of the 21st century, we have to figure out how we're going to live with a fixed amount," FCC Chairman Tom Wheeler said. "Clearly, sharing is key to that."

With the CBRS proposal, the commission abandons "the tired notion" that it must choose between licensed and unlicensed spectrum, added Commissioner Jessica Rosenworcel.

"This is a paradigm shift that paves the way for new services, new technologies and more mobile broadband," she said. "This is big."

The 3.5GHz band is now used mostly by Army and Navy radar systems and satellite equipment. Under the CBRS plan, those incumbent users would share the band with unlicensed users who would gain access by buying an authorized mobile device. The agency also plans to auction short-term licenses to wireless service providers, who would have some protection from interference by the unlicensed users.

Three of the five FCC members expressed some concerns about the proposal, saying the agency has more work to do. In addition to approving the proposal, the FCC voted to open up a new round of public comment to address some continued questions.

The plan allows the U.S. Department of Defense to wall off areas covering about 40 percent of the nation's population into exclusion zones where other users aren't allowed, said Commissioner Ajit Pai. That's more geographic exclusion than is ideal for new services to flourish, he said.

One major question is whether technologies will develop that can manage the "dynamic interference scenarios" that are likely to pop up, Pai added. "It remains to be seen whether we can turn today's spectrum theory into a working reality," he said.

Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's email address is grant_gross@idg.com.

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